The aim of this study is to determine whether full-mouth disinfection therapy(FMT) in our clinical setting would show better improvement of clinical parameters than partial mouth disinfection therapy(PMT) in chronic periodontitis and aggressive periodontitis patients. Among 12 patients, 6 were treated FMT and other 6 were treated PMT. Clinical parameters were calculated 3 months and 6 months after initial therapy. 1. There were no statistically significant differences between FMT and PMT in the reduction rate of bleeding on probing after 3 months, 6 months 2. Initial probing depth was 4-6mm, the mean probing depth after 3 months was 2.2mm vs 2.5mm(FMT vs PMT), after 6 months was 2.4mm vs 2.8mm. This was significantly lower in the FMT groups. 3. Initial probing depth was ${geqq}$ 7mm, the reduction rate of mean probing depth during first 3 months was 4.8mm vs 4.1mm(FMT vs PMT), and 3 to 6 months was 0.5mm vs 0.3mm. This was significantly larger in the FMT groups. 4. Initial probing depth was 4-6mm, the mean clinical attachment level after 3 months was 2.3mm vs 2.7mm(FMT vs PMT), after 6 months was 2.7mm vs 3.0mm. This was significantly lower in the FMT groups. 5. Initial probing depth was ${geqq}$ 7mm, the reduction rate of mean probing depth during first 3 months was 4.0mm vs 3.0mm(FMT vs PMT), and 3 to 6 months was 0mm vs -0.1mm. This was significantly larger in the FMT groups. Although the results provided us with succeccful clinical improvement in aggressive periodontitis, further research is needed to prove its additional benefit in the treatment of chronic periodontitis